This invention relates to a heat exchanger, especially for a motor vehicle.
More particularly, the invention relates to a heat exchanger of the kind comprising a collecting plate provided with a plurality of substantially circular holes, and an array of tubes provided with fins, in which each tube comprises a shaped end, tightly mounted in one of the holes in the collecting plate.
The expression "substantially circular" used herein means that the holes of the collecting plate and the corresponding sections of the ends of the tubes have a circular shape or a shape which may be oval or elliptical determined by a large axis and a small axis of symmetry.
In this kind of heat exchanger, the tightness between each tube end and the collecting plate is most frequently ensured by a joint made from elastomer in the form of a compressible collar which is compressed between the end of the tube and a collar bordering the corresponding hole in the collecting plate. Each tube end may be provided with a bell-mouth obtained by the deformation of the wall of the tube, the function of this deformation being to ensure the retention of the collecting plate on the array of finned tubes and to contribute towards the seal between the tube and the collecting plate.
Furthermore, it is possible to mount a fluid collecting box on one of the ends of the array Of finned tubes thus formed and more particularly on the collecting plate so as to form a heat exchanger.
When used in extreme conditions for this kind of heat exchanger, a phenomenon is produced by which a force directed axially of the tubes has a tendency to move certain tubes in relation to the collector by sliding them in the holes in the collecting plate.
The result of this is to bring about a loss in tightness between the end of the tubes in question and the holes and, in extreme cases, a deterioration of the joint provided between the end of the tube and the hole.
The present invention proposes to minimise or eliminate the above-mentioned problem.